Search results for "dark matter experiment"
showing 10 items of 39 documents
Nuclear Contact Times in Dissipative Heavy Ion Collsions Measured Via γ-Ray Spectroscopy
1987
Electron spectra have been measured for elastic and dissipative U + Au collisions at 8.6 MeV/u and analysed within a simple schematic model which describes γ-ray emission in the presence of a nuclear contact time and a total kinetic energy loss (TKEL). A nearly linear dependence of the mean nuclear contact time τ and TKEL was found, reaching τ = 1.1 * 10-21 s with a variance σ = ±0.4 * 10-21 s for a TKEL of (400 ± 50) MeV.
A simple method for filtering pump fluid vapors from circulated helium
1973
Abstract A simple efficient ceramic filter has been introduced for separation of oil vapors from circulated helium. Oil vapors were observed to pass easily through standard cold-trap and zeolite filters. They behave in these filters in the same way as “carrier fragments” behave in the helium-jet recoil-transport method. The significance of this observation is discussed.
Simulations of the effect of the contact energy levels on a simple model of a hot carrier cell
2016
In the present work, the performance of a simplified model of a hot carrier cell is examined at different energy levels of carrier collection. Incident photons, Monte Carlo generated by employing the ASTM G173-03 data set, are accounted for individually as they interact with the cell. It is assumed that the carriers can be collected ultra-fast, thus avoiding considering hot carrier thermalisation effects. Although the model is preliminary and lacking some mechanisms of hot carrier cells, it has been demonstrated that the present approach to modelling hot carrier solar cells can be developed into fully working models. Some effects of the absorption energy levels in the valence band have been…
Physics reach of the XENON1T dark matter experiment.
2016
The XENON1T experiment is currently in the commissioning phase at the Laboratori Nazionali del Gran Sasso, Italy. In this article we study the experiment's expected sensitivity to the spin-independent WIMP-nucleon interaction cross section, based on Monte Carlo predictions of the electronic and nuclear recoil backgrounds. The total electronic recoil background in $1$ tonne fiducial volume and ($1$, $12$) keV electronic recoil equivalent energy region, before applying any selection to discriminate between electronic and nuclear recoils, is $(1.80 \pm 0.15) \cdot 10^{-4}$ ($\rm{kg} \cdot day \cdot keV)^{-1}$, mainly due to the decay of $^{222}\rm{Rn}$ daughters inside the xenon target. The nu…
A simple model for computing diffuse solar radiation
1989
In this paper a very simple model for predicting the daily diffuse solar radiation at any Italian location using as input few extensively measured meteorological parameters is proposed. In fact the daily diffuse radiation D, MJ.m−2.day−1, here is correlated with only the relative sunshine duration sS and the noon altitude of the sun on the 15th of the month hn, degrees, by the following equation: D=7(sS−(sinhn)1.55 . The validity of this formula is verified using monthly mean daily data from four Italian stations displaced at various latitudes or altitudes or geographical situations (inland or coastal site). The test results show that the deviations between the measured and the computed val…
A simple method for counting the number of trapped ions in an ion trap
1996
The number of stored Ca\(^+\) ions in an ion trap was measured optically by utilizing the metastable states. All the ions trapped are first pumped into the metastable \(D\) states. The ions in the metastable \(D\) states are transferred to the ground \(S\) state via the \(P\) state by exciting a \(D\rightarrow P\) transition. Each ion then emits one photon through a subsequent \(P\rightarrow S\) spontaneous emission. Thus, the number of photons is the same as the number of trapped ions initially in the metastable states. When a fraction of all the stored ions are pumped into the metastable states, the method is still applicable if the fraction of the ions is known.
CP violation and the H-A lineshape
2007
In two-Higgs doublet models (and particularly in the MSSM) the CP-even (H) and CP-odd (A) neutral scalars are nearly degenerate in mass, and their s-channel production would lead to nearly overlapping resonances. CP-violating effects may connect these two Higgs bosons, giving origin to one-loop particle mixing, which, due to their mass proximity, can be resonantly enhanced, altering their lineshape significantly. We show that, in general, the effect of such a CP-violating mixing cannot be mimicked by (or be re-absorbed into) a simple redefinition of the H and A masses in the context of a CP-conserving model. Specifically, the effects of the CP-mixing are such that, either the mass-splitting…
A very simple model for computing global solar radiation
1990
Abstract In this paper a very simple model for predicting the daily global solar radiation at any Italian location using as input of a few extensively measured meterological parameters is proposed. In fact the daily radiation G (MJ m−2) is here correlated only with the sunshine duration s (h) and the noon altitude of the sun on the 15th of the month h n (degrees) by the following equation: G= Ks 0.5 (sin h n ) 1.15 where only one value of the factor K is used. The validity of this formula is verified fixing K = 7.8 and using the data from 34 Italian stations displaced at various latitudes, altitudes or geographical situations (inland or coastal site). The test results show that the deviatio…
PBH assisted search for QCD axion dark matter
2022
The entropy production prior to BBN era is one of ways to prevent QCD axion with the decay constant $F_{a}\in[10^{12}{\rm GeV},10^{16}{\rm GeV}]$ from overclosing the universe when the misalignment angle is $\theta_{\rm i}=\mathcal{O}(1)$. As such, it is necessarily accompanied by an early matter-dominated era (EMD) provided the entropy production is achieved via the decay of a heavy particle. In this work, we consider the possibility of formation of primordial black holes during the EMD era with the assumption of the enhanced primordial scalar perturbation on small scales ($k>10^{4}{\rm Mpc}^{-1}$). In such a scenario, it is expected that PBHs with axion halo accretion develop to ultracomp…
The relaxation dynamics of a simple glass former confined in a pore
2000
We use molecular dynamics computer simulations to investigate the relaxation dynamics of a binary Lennard-Jones liquid confined in a narrow pore. We find that the average dynamics is strongly influenced by the confinement in that time correlation functions are much more stretched than in the bulk. By investigating the dynamics of the particles as a function of their distance from the wall, we can show that this stretching is due to a strong dependence of the relaxation time on this distance, i.e. that the dynamics is spatially very heterogeneous. In particular we find that the typical relaxation time of the particles close to the wall is orders of magnitude larger than the one of particles …